"That hasn't happened before . . ."

pictures (or stories) of hideous injuries sustained by your ariel
will_curry
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Re: "That hasn't happened before . . ."

Postby will_curry » Mon Sep 09, 2019 7:19 pm

That's a thought-provoking diagram . . .

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alan.moore
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Re: "That hasn't happened before . . ."

Postby alan.moore » Mon Sep 09, 2019 11:29 pm

A couple of thoughts and links to previous posts I made on the subject:

There are some sprockets where the holes are oversize for the original bolts... which should have the long shoulder as shown in Will's post. I got Acme to make me up bolts with oversize shoulders which were fine

viewtopic.php?f=4&t=8152&hilit=sprocket

The bolts were originally fitted with locking tabs which, if correctly sized, will prevent the bolts coming loose

viewtopic.php?f=4&t=8063&hilit=sprocket

Acme have these locking washers (I sent him one to copy and he had them at the AGM)

I can see no reason why the bolts should not be loctited in place as well.

John P makes a good point re not using locking nuts where the bolts are still threaded into the hub. The nuts would be OK if the threads in the hub were removed/worn away

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Alan
1939 VH Redhunter;1942 RN WNG;1951 Triumph 6T Thunderbird;1970 BSA B175 Bantam;1986 Yamaha SRX600 single
http://cloggymoore.wix.com/triumph-pre-unit-6t

nevhunter
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Re: "That hasn't happened before . . ."

Postby nevhunter » Tue Sep 10, 2019 8:50 am

Alan (above) describes it correctly The oversize shank is a neat fit in the sprocket holes and originally would all have been a good fit. Going oversize would be formidable unless you just get Acme to do the threads a small bit oversize and I recently made a new sprocket with one less tooth as that was all I had in stock and found indexing the holes to require great accuracy, but I got away with using an old hub and a vertical mill only. You could try some loctite between the bolts area to take the shear force and still be able to check the tightness of all bolts. The bolts as designed do the job of dowels. They originally have tab washers but you could easily improve on the design of them if you tried not too much. I've never had any difficulties until now but these bikes(and us) are not getting any younger. No one would have expected them to be still going in 70 plus years Nev.

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chris.shearwood
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Re: "That hasn't happened before . . ."

Postby chris.shearwood » Tue Sep 10, 2019 5:28 pm

When I was putting together my Sq4 I discovered that a previous owner had attached the sprocket to the hub with bolts of the wrong thread. I forget if they were metric, UNF, UNC or something else. The threads in the hub were not totally ruined so I installed the correct CEI bolts with Loctite but, being afraid to strip the threads completely, I used only a small amount of torque to tighten them up. I naively thought that the bolts would not be likely to unscrew.

400 hundred miles after first starting the bike I decided to go on a short ride over to Lake Champlain, a distance of a little over 50 miles from my house. About half way there I decided to turn back due to violently strong winds and it was lucky I did. I then began to sense something wrong towards the rear end of the bike and even stopped to see if one of the silencers had come loose. I didn't detect any problem so continued on home. Once there, a closer inspection revealed eight of the bolts were gone and the remaining two were loose.

I bought ten 0516Q bolts from Draganfly and installed them with nuts and Loctite but no washers (I can't remember why I wanted stainless bolts because that part of the bike is usually pretty well covered with chain wax and/or oil). I don't remember how tightly the bolts fit into the sprocket holes or even if the bolts had an unthreaded part of the shanks. I did note that the surface of the hub where the nuts sit is not perfectly perpendicular to the bolts but decided it was close enough. I did the nuts up very tight. Since then I have put 1,754 miles on the bike with no further problems in that area. As nothing has unscrewed yet, I suspect that the bodge will hold permanently.
1946 4G, 1950 NG and 1951 VH

david.anderson
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Re: "That hasn't happened before . . ."

Postby david.anderson » Sun Sep 15, 2019 4:38 am

Like Chris I have found that a previous owner has substituted ¼” CEI for 6mm x1mm metric. The 6mm bolt is only .25mm less in diameter and the threads at 25.4 per inch result in an almost normal feeling fit in the ¼” cei hole. When I first purchased it the point advance mechanism in my commando was held in by a 6mm bolt! I have also found 6mm bolts used to replace the studs in the telescopic forks that hold the centre mudguard bracket on the Ariel. Always something to be aware of.
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Re: "That hasn't happened before . . ."

Postby john.whiting » Sun Sep 15, 2019 11:44 am

If you want to fit nuts in a spot like that,you can do a proper job by simply getting some thick washers and bevelling them to suit the angle of fit...............I had a similar thing with my 1200 Harley...all the rivets holding the sprocket ring onto the drum came loose....the 1200 sv doesnt have any form of cush drive anywhere ,and gives the chains a hiding .....I replaced them with 1/4unf gr 8 bolts and nuts,and renewed the bolts every year......they never came loose again......but the tapered wheel studs used to come loose regularly,I always carried a hex key to do them up.....even slopped with red loctite ,they still came loose.


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